ARTHRITIS-ASSOCIATED WITH MONOCLONAL GAMMOPATHY - CLINICAL CHARACTERISTICS

We report nine cases of arthritis associated with a monoclonal gammapa thy. Joint involvement was noted simultaneously or after the diagnosis of monoclonal gammapathy was made. The cases had oligoarthritis or po lyarthritis mimicking rheumatoid arthritis. However, rheumatoid factor was absent in all patients, and distal interphalangeal joints were in volved in two cases and sacroiliitis in one. The plasma cell dyscrasia was a multiple myeloma in two cases and monoclonal gammapathy of unde termined significance in the other patients. The light chain isotype w as kappa in eight of our patients. A type I cryoglobulinaemia was asso ciated in four cases; it was detected in the synovial fluid of two of them. We suggest that the occurrence of paraproteinaemia with chronic arthritis is more than a chance association. Moreover, a monoclonal ga mmapathy should be searched for in patients presenting with atypical s eronegative arthritis.